Trouble activating vista sp1 on a Dell

After upgrading to SP1 I removed the paradox hack and tried both the vista loader 2.1.2 and 3.0.0.1. Neither of them works.

The first gives me an "exception processing message 0xc0000013" error with the title "windows - no disk". Then seems to continue and gives me an ok message. But after rebooting, I see no bootloader message and windows isn't activated.

The second takes its time, gives me an ok message, but after rebooting windows remains not activated.

Hi All,
I have a Dimension 9150 (DXP051) and when I run the installer I get Access Denied. It can't lock the volume to change the boot loader. Now my PC crashed and can't boot. Do you know what I am doing wrong?
Dimitri